Stress distribution in peri implant bone,implants

Stress distribution in peri implant bone,

1. Stress distribution in peri-implant bone, implants, and prostheses: 3D-FEA of marginal bone loss and prosthetic design Şehrize Dilara INCI, Volkan TURP, Firdevs Betul TUNCELLI April2024 PRESENTED BY: Dr. Shubham Jain MDS 2 ND YEAR

2. Content Introduction Material and Methods Results Discussion limitations Cross Reference Conclusion

3. Introduction In clinical dentistry, implant-supported prostheses are the first option to consider for restoring edentulous areas because of their biocompatibility, predictable long-term results, and favorable mechanical properties Given the structural differences between natural teeth and implants, one of the main factors in implant success is how stress is transferred to the alveolar bone The lack of periodontal ligaments around an implant causes forces to be transferred directly to the bone

4. Excessive loads can cause fatigue failure of an implant, resulting in damage to the prosthesis and abutment, and resorption of the peri-implant bone. Parameters such as the mechanical properties of restorative materials and implants, direction of forces, and design of the prosthesis may affect stress formation and distribution on the implant and surrounding bone tissues. Three-dimensional (3D) finite element analysis (FEA) is a practical method that evaluates the stress distribution in areas of complex geometry, such as the interface between an implant and bone

5. Computer-aided design/computer-aided manufacturing (CAD/CAM) enables clinicians to create monolithic models of various materials with varying elastomeric properties that can be applied to implant-supported prostheses. There have been a number of studies conducted to identify materials and prosthesis designs that can tolerate stress in implant-supported fixed prostheses. However, the results have shown conflicting results and to date no optimal solution has been identified. This study evaluated the stress distribution in implants, peripheral bone, and prostheses by using the 3D FEA method to model different restorative material types, load angles, prosthesis designs, and bone heights.

6. MATERIAL AND METHODS Two models representing the right mandibular molar bone section with different amounts of marginal bone loss were created geometrically using a computer software. The specifications were 2 mm cortical and 25.067, 58.300, and 35.636-mm thicknesses on the x-, y, and z-axes, respectively. The two models were converted to the Standard Tessellation Language (STL) format to make them eligible for analysis. Three regular titanium implants (Bone Level CrossFit SLA Implant; 4.1 × 12 mm, Institute Straumann® AG, Basel, Switzerland), titanium abutments (RC Variobase for Crown; Straumann) 4.5 mm in diameter and 5.5 mm in height.

7. Their inner screws were scanned with Activity 880 (Smart Optics Sensortechnik GmbH, Sinterstrasse 8, D-44795 Bochum, Germany) to analyze stress on the crown, implant, and peripheral bone. Computer-generated data from the lower and upper structural parts of the prosthesis, implant screws, and bone tissues were harmonized using Boolean operations. The results for the cortical and cancellous bone were recorded separately. The bone structure of the model was fixed in all directions. A static load was applied vertically (90°) and obliquely (30°).

8. A vertical load was applied to the central fossa and buccal cusps, whereas an oblique load was applied only to the buccal cusps. The vertical load was 500 N and the oblique load was 250 N. . In each direction of force (vertical and oblique), the total load was divided such that the force at each point of application was equal (e.g., a total load of 500 N was divided such that five loading points [buccal cusps, central fossa, and three others] each received 100 N force). .The loading points were determined according to the implantsupported prosthesis occlusal scheme. One model simulated 0 mm marginal bone loss with a splinted crown design, and the second simulated 3 mm marginal bone loss with a nonsplinted crown design

9. In both models, the implants were located in the second premolar, first molar, and second molar areas. The threedimensional components of the crowns were modeled as monolithic. The gingiva was ignored in both models, and a cement layer was generated between the abutment and crown to mimic clinical conditions . The resin cement thickness was assumed to be 0.3 mm [20]. Four different materials were used for the prosthetic structures: hybrid ceramic (HC), resin-nano ceramic (RNC), lithium disilicate ( LiSi ), and zirconia (Zr).

10. The elastic modulus values and Poisson’s ratios (i.e., physical property measures) for the investigated material types and structures were derived from the literature. The implants were assumed to be 100% osseointegrated . Stress distribution in the peripheral bone was evaluated using Maximum and Minimum Principal Analyses, and stress values in implants and prosthetic structures were evaluated using von Mises analysis.

11. RESULTS

12. Under oblique loading, various restorative materials generated different maximum and minimum principal stress values in cortical and cancellous bones LiSi exhibited the highest maximum principal stress value in Model 1 (34.42 MPa), and Zr exhibited the lowest maximum principal stress value in Model 2 (1.5 MPa). The maximum and minimum physiological stress limits of the cortical bone (173 MPa and 100 MPa, respectively) were not exceeded in either model under any of the scenarios tested. When each restorative material was analyzed individually, the total stress values for the cortical bone were identical .

13. Under vertical loading, the effects of the two different prosthesis designs on cortical and cancellous bones were similar. However, the splinted prosthesis design under oblique loading resulted in a more favorable stress distribution than the non-splinted prosthesis design In Model 1 , the maximum and minimum stresses occur in the distobuccal region of the cortical bone under vertical loading. In the cancellous bone, the maximum and minimum principal stresses were concentrated in the buccal region of the bone In Model 2 , the maximum and minimum stresses were concentrated in the distal region of the cortical bone under vertical loading In the cancellous bone, the maximum and minimum principal stresses were concentrated in the palatal and buccal regions of the bone

14. The splinted prosthesis design generated more stress around the implants than the non-splinted design. In both models, the highest stress values were concentrated at the buccal tubercles, force application sites, central fossa, contact areas, and marginal finishing line

15. In Model 1, the stresses that occurred at the occlusal surface were more widespread than those observed in Model 2. The highest von Mises values were recorded for Zr in Model 2 (178.61 MPa) and the lowest von Mises values were observed for RNS in Model 1 (20.6 MPa). The splinted prosthesis design generated favorable stress values for the restorative crowns

16. Discussion The results of this study indicate that none of the restorative materials tested have significant effects on the peri-implant bone; however, the load angle and prosthesis design may have a significant impact on stress generation. Although this is a theoretical study that assumes ideal bonding conditions for each scenario, the findings for material mechanics are of scientific significance Teeth and cortical bone have similar moduli of elasticity, whereas titanium implants have a modulus of elasticity 5 or 10 times greater. Thus, the load on the tooth does not create much stress at the crest interface, whereas the load on the implant may cause significant stress on the bone even if it is partially transmitted

17. To analyze stress on the crown, implant, and peripheral bone, we used two models for simulating a 0 mm and a 3 mm marginal bone loss with different prosthesis designs. As the oral environment is dynamic, occlusal forces are applied in multiple directions, resulting in a leverage effect on the oral bone. As in the present study, investigations conducted using FEA should combine different angulated forces to mimic oral conditions . In line with several previous studies, the present study demonstrated that oblique loading causes more significant stress on cortical and cancellous bone tissue than vertical loading

18. Cortical bone has a higher elastic modulus than cancellous bone making it more resistant to occlusal forces and deformation. Thus, cortical bone tissue is more resistant to stress than cancellous bone tissue and forms a stronger bond with implants . The current study demonstrated that stresses in peri-implant cortical bone tissue are higher than those in cancellous bone and that stresses decrease towards the apex. The different restorative materials did not significantly affect the loads transferred to the peri-implant bone

19. limitations The stress distribution findings may not fully capture the nuanced variations associated with different bone densities, as the jaw models utilized in this investigation were of standard density. The study adopted a uniform occlusal geometry, potentially overlooking diverse stress patterns that could arise from variations in occlusal configurations. Moreover, finite element analysis (FEA) assumes linear, homogeneous, and isotropic properties in models, yet the real clinical environment is notably heterogeneous. Despite assuming 100% osseointegration for all implants, the clinical reality of varied osseointegration levels remains unaccounted for in the models and calculations.

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21. Cross reference

22. Conclution This study provides crucial insights the occurrence of stresses implant-supported prostheses. In every investigated scenario, the oblique loading generated more stress. The type of restorative material did not significantly affect the stress distribution in the supporting bone and implant. Resin-infiltrated restorative materials generate favorable stresses in prosthesis limitations, particularly in marginal finish areas. The splinted prosthesis design resulted in less stress on bone support. a splinted design may be preferable in the presence of parafunctional habits. Overall, the results for the splinted and non-splinted prosthesis designs were comparable.

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